1. Field of the Invention
Aspects of the present invention relate to a battery pack, and more particularly, to a temperature compensated current measuring device which can measure current flowing in a conductor, and a battery pack using the same.
2. Description of the Related Art
Generally, a secondary battery can be rechargeable and thus repeatedly usable, which is different from a primary battery. The secondary battery is generally used as the main power of portable devices for communication, information processing, and audio/video. Currently, interests in the secondary battery are being increased and the development of the secondary battery is also being rapidly performed. The main reason thereof is because the secondary battery is a super-light, high energy density, and environment-friendly battery with a high output voltage and a low electric discharge rate, and also because the secondary battery is a power source with a comparatively longer lifespan.
Secondary batteries are classified into nickel-metal hydride (Ni-MH) batteries, lithium ion (Li-ion) batteries, and the like, based on electrode active materials. Particularly, the lithium ion (Li-ion) batteries may be classified based on the type of electrolyte, for example, when liquid electrolyte is used and when solid electrolyte or gel-type electrolyte is used. Also, the secondary batteries are classified into various types, such as a can type, a pouch type, and the like, based on the shape of a can within which the electrode assembly is received.
The weight-to-energy density of the lithium ion (Li-ion) battery is much greater than the primary battery and thus can be manufactured as a super-light battery. Also, the average voltage of the lithium ion (Li-ion) battery for each cell is about 3.6V and is compact by three times, in comparison with the average voltage, about 1.2V, of other secondary batteries, such as a Ni—Cd battery and a nickel-metal hydride (Ni-MH) battery. Also, the lithium ion battery has an electric discharge rate of less than 5% a month in the temperature of about 20° C., which is about one third of the electric discharge rate of the Ni—Cd battery and the nickel-metal hydride battery. Also, the lithium ion battery does not use heavy metal, such as cadmium (Cd) and mercury (Hg) and thus is environment-friendly. Also, the lithium ion battery can be rechargeable at least one thousand times in a normal state. Accordingly, with developments in information communication technologies, there is an increase in research on secondary batteries based on the above-described advantages.
Also, in the situation of a rechargeable secondary battery, a plurality of secondary batteries is mounted to a portable electronics product, such as a notebook personal computer (PC) in a form of a pack, and thereby used. In this instance, a charging/discharging control circuit is embedded in the pack-type secondary battery and controls general matters about charging/discharging the battery. Also, the charging/discharging control circuit prevents overcharging or over-discharging of the battery, thereby improving battery stability. Also, the charging/discharging control circuit measures the current in the situation of charging/discharging of the battery, and thereby controlling the charging and discharging.
In this instance, the charging/discharging control circuit has an external resistor located at one position of a conductor in which current flows, and measures the current flowing in the external resistor by measuring the resistance value of the external resistor and a voltage value between both ends of the external resistor. When high-current flows in the external resistor, the voltage value between both ends of the external resistor also significantly changes.
Accordingly, a battery pack, such as a high-capacity battery pack, and the like, flows high-current in the external resistor. According to the flow of the high-current, the voltage value across both ends of the external resistor significantly changes. However, when the measurement scope of the voltage value is extremely broad, the actual current flowing in the external resistor may not be accurately measured. Accordingly, charging/discharging of the battery may be ineffectively controlled.